The present invention relates to a golf club set in which low-numbered golf clubs are lowered in the gravitational center of the head.
In order to derive full performance from a club which is proper to the number of the club, devices were made with respect to the gravitational center of the head and the moment of inertia of the head.
In general, it is relatively difficult for the average golfers to hit a ball high towards an intended direction with a long iron having a small loft angle for example. Therefore, devices to make the gravitational center of the head lower and deeper were made for such a golf club.
For example, U.S. Pat. Nos. 5,501,459 and 5,807,191 disclose golf clubs of which head is provided with a sole made of a very high specific gravity material. U.S. Pat. No. 539,712 discloses a golf club in which the main portion of the head is formed in a shape of low gravitational center. In the former case, the head tends to become complex. In the later case, the possibility of head design is greatly restricted.
It is therefore, an object of the present invention to provide a golf club set, in which low-numbered golf clubs can be lowered in the gravitational center of the head, without imposing a complex structure and limiting the head design freedom.
According to the present invention, a golf club set comprises
at least three golf clubs having different loft angles changing progressively from the smallest loft angle of the lowest numbered golf club to the largest loft angle of the highest numbered golf club,
each of the golf clubs comprising a shaft and a head, the head provided with a hosel having a shaft inserting hole into which the shaft is inserted,
in a standard state of each golf club in which the head is disposed on a horizontal plane so as to show its lie angle and loft angle, the clubs satisfying the following conditions
Lnxe2x89xa6L(n+1)
L(n=1) less than L(n=m)
i dnxe2x89xa7d(n+1)
d(n=1) greater than d(n=m)
xe2x80x83wherein
L is a hosel length,
d is an inside diameter of a shaft inserting hole, suffix xe2x80x9cnxe2x80x9d to xe2x80x9cLxe2x80x9d and xe2x80x9cdxe2x80x9d means the order number of the club in the ascending order from the lowest numbered club (n=1) to the highest numbered club (n=m), and
m is the number of the golf clubs, and
the hosel length of each club is defined as a length measured from the upper end of the hosel to the horizontal plane along the central axis of the shaft.